I'm on the train going up the cavalo
mountain in Rio de Janeiro in Brazil
going to see one of the most famous
monuments in the whole of Brazil the
statue of Christ the Redeemer and we're
going to talk about some interesting
chemistry when we get there there is a
story that Albert Einstein traveled on
this train so this is really a homage to
him as well
so here we are on the summit of the
kavado and behind me is the famous
statue of Christ the
Redeemer it's nearly 130 ft High just
under 40 m high and 30 m wide and there
are a huge number of people here the
statue is made from soap stone it's a
very soft Stone and inside
it has concrete reinforced with iron
rods steel rods to give it strength but
soap stone is one of the softest Stones
you can have and it is very similar in
chemical composition to baby powder
talc this sort of powder that you put on
babies chemically talc is derived from
magnesium silicate magnesium and sio4 2
minus
ions and because it's ionic and has
discrete ions in the structure it's
quite soft it's easy to break up but
soap stone is related to tal but has
been under the ground high pressure and
high temperature and it is transformed
into a stronger Rock but it's still
really quite soft and you can cut it
quite easily so you can sculpt the head
of Christ the statue doesn't fall apart
because although the soap stone is very
soft it's just on the surface the whole
surface is covered with triangles of
soap stone rather like a mosaic and
these have been cut to give the features
of
Christ and soapstone is a very nice and
smooth smooth Rock it feels rather like
the talc when you put it on your skin it
makes your skin all soft and smooth
that's why they put it on
babies now we can't go near the statue
because it's far too high where the soap
stone starts but Brady's thought of that
and he's b a
backup so I have in here a small statue
made of soap stone
you can see it looks just the same as
the real thing but when I stroke the
stone it feels just like soap and you
can see it has been carved really quite
intricately and easily because the so
stone is so soft the erosion of stone is
often caused by very bad weather snow
and ice because when water freezes it
breaks up the stone and here we are in
Rio one of the warmest cities in the
world though it doesn't feel like that
today and so there's very rarely any
Frost and that is why it isn't
damaged but it has been damaged by
lightning and because it's right at the
top of a mountain and about four or five
years ago it was struck by lightning and
required quite extensive restoration to
repair the damage so now it has got
several lightning conductors
probably made of copper to conduct the
electricity down without damaging the
stone we've now got to the base of the
statue and in the guide books they don't
really say anything about the base and
the base is made or is covered with
Marble Marble is calcium
carbonate and you can polish it to a
high brightness it's almost like a
mirror you might be able to see my face
inside it reflected in it and I think
they chose this because it looks nice
but I think there's another reason and
the reason is that marble is much harder
than soap stone and I think they chose
it to stop people scratching their names
onto the stone because even with a
barrow you could scratch soap stone and
so in the 80 years it's been here there
would be hundreds of names over it but
the marble you can see is still as good
as
[Music]
new I think it's look really
very
impressive it really looms over you
dominates this crowd of people and from
the center of the Town it looks really
mysterious especially on a day like
today when there are lots of clouds and
Christ appears through the clouds and
then disappears again it's really very
effective and the science is also
interesting but there is also one fact
which is quite surprising is that this
mountain is made out of a different Rock
it's made out of granite which is one of
the hardest minerals so there is
something very symbolic about the Statue
of Christ which is very soft standing on
the hard
Earth and I'm sure many people can read
all sorts of significance into that I
don't read any significance except as a
fantastic demonstration of the different
different powers of materials how
different chemical composition can give
you such different properties